Current Events
by Leslie T. Waldorf
Ocean Challenge

At a Snail's Pace
from Class Afloat News, November 4, 1996

The slowest snail in the world traveled less than two feet a year. At this rate, it was one of the slowest creatures on the planet. About an inch long, this small snail species named Partula turgida began its existence in 1.5 million B.C. Then, in January 1996, it went extinct after a decade-long struggle to survive. The last Turgi, as they were fondly called, died in a specimen box in the London Zoo.

Over the millennia the Partula genus evolved into 117 different species. Springboarded into this diversity by their freedom from predators, these tree snails thrived in the Society Islands (northwest of Tahiti). This all changed in 1967 when the giant African snail was imported to farm commercially because the locals liked to eat them. When the species escaped from their controlled habitat, locals could not stop their population from growing with fire or poison. In 1978, a Florida snail was introduced in hopes that it would become a predator of the African snail.

Nature, however, has long resisted man-made forms of controls. Restoring the balanced environment proved difficult: the Florida snail preferred the taste of the endangered tree snail over the giant African one. The result was a loss of 27 species of Partula.

Scientists have compared these snails in importance to Darwin's finches. They have not only taught us about evolutionary theory, but as one invertebrate scientist notes about the now extinct Partula turgida, "Species extinction is an almost certain daily phenomenon but actual documented cases of loss are relatively rare."

Earlier this year scientists from Great Britain set out to rescue some of the other Partula species. They relocated specimens of three different species to their home island of Moorea, near Tahiti, where they are now in a preserve protected from predators. The spot is 20 square meters of rainforest that is enclosed by both an electric fence and a salt water moat. Numbers have dramatically increased. "One of the species was down to just four individuals. But we have a thousand now," reports the head keeper of invertebrate conservation at the London Zoo.

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